JP2773261B2 - Method for producing fiber-reinforced thermoplastic resin molded article - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fiber containing a short fiber as a reinforcing fiber, and particularly suitable for obtaining a molded article having a complicated shape such as a branch pipe or a joint. The present invention relates to a method for producing a reinforced thermoplastic resin molded article.

[Related Art] Conventionally, the following method is known as a method for producing a molded article made of a resin reinforced with fibers.

A. An injection molding method in which a molten thermoplastic resin and reinforcing short fibers are kneaded and injection molded in a mold.

B. In a heating chamber provided near the mold,
Put the preform material of thermoplastic resin and short fiber for reinforcement,
A transfer molding method in which the resin of the preform material is heated to melt and injection molded into a mold.

C. Sheet molding compound (SM) consisting of uncured thermosetting resin and reinforcing fibers between upper and lower molds
A compression molding method in which molding materials such as C) and bulk molding compound (BMC) are charged, and the upper and lower dies are moved relative to each other while heating to form them under pressure.

Etc. are known.

For example, a method for producing a molded article having a relatively complicated shape as shown in FIGS. 4, 6 and 7 includes: A. Unstrengthened thermosetting resin A sheet winding method, in which the resin is heated and cured, and the mandrel is pulled out, B. The reinforcing fiber and its tape are wound around the mandrel while impregnating the uncured thermosetting resin with the resin. A filament winding method, in which a mandrel is extracted after hardening, is known.

[Problems to be Solved by the Invention] However, the injection molding method has a length of several mm before molding.
Most of the relatively long reinforcing short fibers are broken in the kneading process in the molding machine or in the injection process passing through a narrow gate, so it becomes shorter than 1 mm in the molded product,
There is a problem that a molded article having high mechanical strength cannot be obtained.

Further, the transfer molding method does not have a kneading step, but has an injection step, so that there is still a problem that many reinforcing short fibers are broken or bent.

Furthermore, in the molded body obtained by these methods, the short fibers for reinforcement flow into the mold through the gate together with the molten resin at the time of molding, so that the short fibers are regulated at the position of the gate and oriented in a specific direction. , The isotropy is reduced. In addition, to provide a gate in the mold, at the merging position of the flowing resin,
There is a disadvantage that a portion having low mechanical strength called a so-called weld line occurs.

In the compression molding method, since no gate is used, no weld line is generated in the molded body, and either long fibers or short fibers can be used as reinforcing fibers, and the orientation direction of the fibers can be freely set. Although there is an advantage that it can be performed, it is difficult to push a molding material into a narrow cavity when manufacturing a molded body having a sharp rim portion or a molded body having a large change in wall thickness.

As a method for solving this problem, Japanese Patent Publication No. 60-29613 discloses a method in which a plurality of molds divided into three or more parts are used, and the resin is preliminarily molded into the shape of the final molded body. And a method of compressing and molding the preformed body from a plurality of directions. However, this method has a problem that the resin and the reinforcing fiber do not flow into narrow details in the mold because the resin does not enter a molten state unlike the injection molding method, and the problem has not yet been solved.

On the other hand, in the sheet winding method and the filament winding method, since the reinforcing fibers to be used are long fibers, the strength of the obtained molded body is relatively high, but the molded body having a different cross-sectional shape in the longitudinal direction, and complicated When a shaped article is obtained, it is difficult to wind the fiber around the mandrel or to remove the mandrel, and thus there is a problem that the molding is very difficult.

The present invention provides a molded article having a high mechanical strength, particularly a molded article having a complicated shape, in which the breaking of the reinforcing fiber is small, the orientation of the short fiber is easily controlled, and the occurrence of a weld line can be prevented. An object of the present invention is to provide a method for producing a fiber-reinforced thermoplastic resin molded article that can be easily obtained.

[Means for Solving the Problems] The present invention for achieving the above object is as follows.

(1) A method in which a plurality of preformed bodies containing short fibers for reinforcement and a thermoplastic resin are arranged in layers in a mold, and heated / pressed to produce a formed body made of a fiber-reinforced thermoplastic resin. A. A mold having at least two split molds is used as the mold; b. At least one of the plurality of preforms is in one direction in which short reinforcing fibers are aligned in one direction Using the preform, c. Placing the unidirectional preform adjacent to the cavity of the mold, which molds the part of the molded body where one-way reinforcement is desired, d. Heating the mold Melt the thermoplastic resin of the preform and relatively move the split mold.e. Make the short fibers for reinforcement contained in the one-way preform flow with the molten thermoplastic resin and move in the direction of the flow. Orienting a fiber-reinforced thermoplastic resin molded body Manufacturing method.

(2) The method for producing a fiber-reinforced thermoplastic resin molded article according to claim 1, wherein the one-way preformed article is arranged so that the direction of the short fiber is orthogonal to the moving direction of the split mold.

(3) a preform containing short fibers having a length of 5 mm or more and formed into a tape or a strand is used;
A method for producing the fiber-reinforced thermoplastic resin molded article according to claim 1.

(4) A tubular fiber-reinforced thermoplastic resin molded article is molded by using a mold having a female mold having a cylindrical cavity and a male mold inserted into the cavity. The method for producing a fiber-reinforced thermoplastic resin molded article according to the above.

(5) A method comprising: arranging a sheet containing long fibers for reinforcement and a thermoplastic resin on at least a part of the cavity along an inner peripheral surface thereof, and then arranging a preform inside the sheet and performing pressure molding. Item 5. The method for producing a fiber-reinforced thermoplastic resin molded article according to Item 4.

(6) The method for producing a fiber-reinforced thermoplastic resin molded article according to claim 5, wherein the long fibers are made of carbon fibers.

(7) The preform formed in a plate shape is used.
7. The method for producing a fiber-reinforced thermoplastic resin molded article according to any one of claims 6 to 6.

(8) The method for producing a fiber-reinforced thermoplastic resin molded article according to any one of claims 1 to 7, wherein the short fibers are made of carbon fibers.

Here, as the reinforcing short fibers and long fibers, glass fibers, carbon fibers, ceramic fibers, metal fibers, synthetic fibers, and the like can be used, and carbon fibers are particularly preferable. Further, those having a tensile strength of 30 kg / mm ² or more, those having a Young's modulus of 1,000 kg / mm ² or more, and those in combination are also preferably used. In addition, the length of short fibers is 5m
m or more, more preferably 5 to 51 mm, and most preferably 5 to 30 mm. Further, the thickness of the short fiber and the long fiber is preferably in the range of 1 to 50 μm.

Examples of the thermoplastic resin include polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene-butadiene-acrylonitrile copolymer, styrene-acrylonitrile copolymer, polyamide, polycarbonate, polysulfone, polyacetal, and polymethyl methacrylate. And resins such as polyphenylene oxide, thermoplastic polyurethane, polyethylene terephthalate, polybutylene terephthalate, polyether ether ketone, and polyphenylene sulfide. Also, a mixture of two or more of these resins can be used. To these resins, a plasticizer, a heat stabilizer, a light stabilizer, a filler, a face wash, a processing aid, an impact modifier, an extender, and the like may be added.

The preform contains the above short fibers and a thermoplastic resin, and the amount of the short fibers is preferably 20 to 70%, more preferably 40 to 60% in terms of fiber volume content. .

The sheet containing the reinforcing long fibers and the thermoplastic resin is a sheet formed by mixing the above long fibers and the thermoplastic resin, and the length of the long fibers is preferably more than 51 mm, and is preferably formed. It is more preferable that the molded article has a full length or a half or more of the entire length. The amount is
Preferably, the fiber volume content is 35 to 70%,
More preferably, it is 6060%. Further, the long fibers are preferably oriented in the length direction of the sheet.

The arrangement of the long fibers in the cylindrical cavity is preferably on the entire surface of the cavity, but may be on a part of the surface.

The pressure in the pressure molding is preferably 10 kg / cm ² or more. The heating temperature is a temperature equal to or higher than the melting point of the thermoplastic resin.

[Action] In the method of the present invention, a preform containing reinforcing short fibers and a thermoplastic resin is placed in a mold, and when subjected to heat and pressure molding, the one-way preform is subjected to the above-mentioned molding process. After arranging the part to be strengthened in one direction in the molded body (part where mechanical stress such as large tensile stress or bending stress acts when using the obtained molded body) is placed adjacent to the cavity for molding, The mold is heated to melt the thermoplastic resin of the pre-formed body and relatively move the split mold, and the reinforcing short fibers contained in the one-way pre-formed body are caused to flow together with the molten thermoplastic resin. Orient in the direction of flow.

Therefore, the molded article obtained by the method of the present invention is excellent in mechanical stress such as tension, bending, torsion, and shear.

Example 1 Example 1 FIGS. 1 and 2 illustrate a method according to claims 1 and 2, and FIG. 1 shows an upper part for molding a molded article having a bowl-shaped cross section. FIG. 2 is a longitudinal sectional view of a mold composed of a mold 1 and a lower mold 2, and FIG. 2 is a longitudinal sectional view of the mold showing a state where the upper mold 1 in FIG. This example shows a case where it is desired to give mechanical strength to the cylindrical convex portion of the bowl-shaped molded body, that is, a case where the orientation direction of the short fibers is desired to be aligned in the cylindrical concave portion 3 of the mold 2.

In the figure, 1 is an upper mold (male type) having a hemispherical convex portion 4 for forming a bowl-shaped inner peripheral surface, 2 is a hemispherical concave portion 5 for forming a bowl-shaped outer peripheral surface, A lower mold (female mold) having a cylindrical concave portion 3 at the bottom is shown, and a cup-shaped cavity 7 is formed between the molds by fitting the molds at the side portions 6. The molding is performed by moving the upper mold 1 downward in the figure.

8 to 10 are preforms. These preforms 8 to
Of 10, the preforms 8 and 9 are preforms in which the orientation direction of the reinforcing short fibers is random,
Is a unidirectional preform in which short fibers are aligned in one direction. When the short fibers in the preform 10 are arranged in the lower mold 2, they are aligned in a direction orthogonal to the moving direction of the upper mold 1 during molding. The preforms 8, 9
May also be a one-way preform.

The preforms 8 to 10 may be molded by placing reinforcing short fibers in a cavity of a mold and filling the cavity with a thermoplastic resin melted by an injection molding machine or the like. May be placed in a mold and subjected to hot press molding. The shapes of the preforms 8 to 10 are
The thermoplastic resin is sufficiently impregnated between the short fibers, and
Any shape may be used as long as it can be easily molded by a simple injection molding method or a hot press molding method. Usually, a disk-shaped, elliptical-plate-shaped, or rectangular-plate-shaped one is used. Since the preform is melted at the time of molding, it may contain some voids or the like.

In the molding, first, a release agent is applied to the shaping surfaces 1 ', 2' of the upper mold 1 and the lower mold 2, respectively. Then, the preforms 8 to 10 are arranged in the cavity 7 as shown in FIG. At this time, the preform 10 is formed such that the direction of the reinforcing short fibers is orthogonal to the moving direction of the upper mold 1, and
It is arranged so as to be adjacent to the cylindrical concave portion 3 for molding a portion to be strengthened in one direction. In this state, the upper mold 1 and the lower mold 2
Is heated above the melting point of the thermoplastic resin of the preforms 8 to 10, and then the upper mold 1 is moved downward along the side portions 6.
Then, a bowl-shaped cavity 7 is formed as shown in FIG. 2, and the molten resin flows to every corner of the cavity 7. At this time, the resin of the preforms 8 and 9 is
Since it is directly subjected to pressure from the upper mold 1, it mainly flows in the direction of the side portion 6 and downward. However, since the resin of the preform 10 receives pressure in the direction of the lower mold 2 via the preform 9, almost all Flows into the lower cylindrical recess 3. Therefore, the short fibers in the preforms 8 and 9 are mainly oriented in the left-right direction in the figure at the bottom of the concave portion 5, but the short fibers flowing into the concave portion 3 are melted together with the molten resin flowing from the inlet 11.
It rotates nearly 90 ° and is oriented in the direction of flow of the molten resin. Therefore, in the concave portion 3, most of the short fibers are vertically oriented, and a bowl having high mechanical strength can be obtained.
That is, in consideration of the flow direction of the thermoplastic resin at the time of molding, the one-way preformed body is arranged adjacent to the cylindrical concave portion 3 for molding a part of the molded body where one-way reinforcement is desired. The orientation direction of the short fibers of the molded article can be controlled relatively freely.

In the above-described example, the bowl-shaped final molded body is taken out of the lower mold 2 after the mold is cooled. In order to facilitate the take-out, as shown in FIG. May be divided into two. Further, in order to avoid insufficient pressurization due to shortage of the molten thermoplastic resin at the time of pressurization by the upper mold 1, the volume of the preformed body may be slightly larger than the volume of the cavity 7. In addition, molten thermoplastic resin,
As shown in FIG. 1, when the inflow port 11 is caused to flow into the narrow and long cylindrical recess 3, the short fibers may break due to contact with the inflow port 11 or the short fibers may not flow sufficiently. In such a case, another preformed body which has been fragmented may be arranged in the concave portion 3.

Example 2 FIGS. 3 and 4 are for explaining the method according to claim 4, and FIG. 3 shows a state in which a preform is arranged for producing a tubular molded body. FIG. 4 is a perspective view of a molded product manufactured using the mold shown in FIG.

In the figure, 12 is an upper mold, 13 is a lower mold, and a semicircular cavity 14 having a radius of 15 mm is formed in both molds, and a concave portion of the upper mold is formed.
By fitting the projection 15 of the lower die to the projection 16 of the lower die, a cross-shaped cavity having a diameter of 30 mm is formed. The upper mold 12 and the lower mold 13 form a female mold. Meanwhile, male 17
Is inserted into a female cross-shaped cavity to regulate the inner diameter of the tubular molded body, and has a tip 18 having an outer diameter of 26 mm, which is slightly smaller than the inner diameter of the cavity. Reference numeral 20 denotes a fixing bolt for connecting the upper die 12 and the lower die 13.

On the other hand, a carbon fiber of 6,000 single yarns was aligned and impregnated with nylon 6, having a thickness of 100 μm and a width of 4 mm.
Of a tape-shaped unidirectional preform of length 10
Cut to ~ 30mm. Next, the cut preform is filled in a separately provided mold, and is heated and pressed under the conditions of 250 ° C. and 100 kg / cm ² , and has a diameter of 10 to 30 mm and a thickness of 3 to 6 m.
A plurality of disc-shaped preforms 19 each having a fiber volume content of about 60%, which differ in the range of m, were formed.

Next, the plurality of preforms 19 are placed in the cavity 14 of the lower mold 13 as shown in FIG. 3, the upper mold 12 and the lower mold 13 are fitted, and both molds are tightened with fixing bolts 20. And integrated. At this time, in the molded body shown in FIG. 4, the length of the short fiber is particularly long in the portion of the cavity for forming the portion of the crossing portion 22 where particularly high mechanical strength is required, and the orientation of the short fiber is A preformed body having a surface direction was arranged.

Next, after heating the mold to heat the preform 19 to 230 to 250 ° C., the four male molds 17 were moved in the direction of the arrow in FIG. 3 at a pressure of 30 kg / cm ² .

After maintaining this pressurized state for 3 minutes, the mold was cooled and the molded body was taken out. As shown in FIG.
Was obtained, a cross-shaped molded body 23 having an opening 21 on all sides having a thickness of 30 mm, a wall thickness of 2 mm, and a length L of the longest portion of 300 mm. When the fracture bending stress of this molded body 23 was measured, it was 40 kg / mm ^2, which is very high as a molded body of this type, and is suitable for use in a pipe joint where strength is required at a connection portion, for example. Met.

Embodiment 3 FIG. 5 is a perspective view showing a tubular molded body obtained by the method according to claim 5.

In the figure, a straight tubular molded body 24 having a circular cross section is an outer layer containing nylon 6 and a plain woven cloth (long fiber) of carbon fiber.
25 and an inner layer 26 containing nylon 6 and long carbon fibers.
And an intermediate layer 27 containing nylon 6 and glass fiber chopped strands (short fibers) having a length of 13 mm.

The long fibers of the inner layer 26 are oriented in the axial direction of the molded body 24. However, in consideration of various mechanical strengths, the inner layer 26 may include, for example, fibers in a direction of ± 30 to ± 45 ° with respect to the axial direction, in addition to the long fibers in the axial direction.

The short fibers in the mid layer 27 are preferably oriented in the axial direction of the molded body 24, but may be random. The same applies to those shown in FIGS. 6 and 7 described later.

Further, in this embodiment, the long fibers are arranged in the outer layer and the inner layer, but may be arranged in at least a part of the outer layer.
Thus, when the long fibers are arranged in the inner and outer layers, particularly in the outer layer,
Even when a bending stress or a torsional stress acts on the tubular molded body 24, the molded body can sufficiently withstand the stress, and a molded body having higher strength than a molded body reinforced only with short fibers can be obtained.

Example 4 FIG. 6 is a perspective view of a Y-shaped molded body having a non-circular cross section. In the figure, the molded body 28 is made of nylon 6 and
A main layer 29 containing short glass fibers having a length of 6 mm;
And a surface layer 30 including a carbon long fiber having a length of 150 mm. The main layer 29 has a hole 31 inside, and the upper and lower surfaces are chamfered in parallel on the outer periphery, and the surface layer 30 has a long fiber in the chamfered surface in the axial direction of the molded body 28. It is arranged to become.

When the cross section is made non-circular in this way, a large amount of long fibers can be arranged on the surface layer on which bending stress, torsional stress, etc. act, so that a molded article with extremely high strength can be obtained.

The molded body 28 of this embodiment can be manufactured by the method described in FIG. 11 in which the cavities 43a and 43b of the mold shown in FIG.

Example 5 FIG. 7 is a perspective view of a cross-shaped molded body having a non-circular cross section, which is also a modification of the molded body shown in FIG. In this example, the cross-sectional shape of the main layer 47 containing the reinforcing short fibers is made hexagonal, and the surface layers 34a and 34b of long fibers are arranged on the upper and lower surfaces so that the direction of the fibers is along the axial direction of the molded body 32. is there.

Embodiment 6 FIG. 8 is an exploded view for explaining the method of manufacturing the straight tubular molded body 24 described in FIG. 5, and FIG. 9 shows a U-shaped tape 36 used in this method. FIG. 10 is a perspective view,
FIG. 9 is a longitudinal sectional view of a mold showing a state where the male mold 37 in FIG. 8 is inserted into the female mold 38. This example corresponds to the method according to claims 4 and 5.

Hereinafter, a method of manufacturing the molded body 24 shown in FIG. 5 will be described in the order of steps.

First, in FIG. 8, a cylindrical cavity 39 of the female mold 38 is provided.
Then, a plain woven cloth 40 impregnated with a thermoplastic resin is rounded into a cylindrical shape as shown in the figure, and inserted along the inner peripheral surface of the cavity 39. Next, a plurality of disc-shaped preforms 19 containing reinforcing short fibers are inserted. At this time, the preform 19 used is one in which the direction of the short fiber is oriented in the direction of the plate surface, and is inserted so that the short fiber is in a direction orthogonal to the moving direction of the male mold 37 described later. Also,
The preform 19 constitutes the intermediate layer 27 of the molded body 24 shown in FIG. 5, and the required number thereof is obtained in advance by calculation.

Next, as shown in FIG. 9, a plurality of tapes 36 obtained by impregnating a thermoplastic resin 42 into one in which long fibers 41 are aligned in one direction and bending the tape into a U-shape are combined as shown in FIG. An aggregate 35 is formed, and this is
Insert and place on both sides of 19.

Next, the female mold 38 is heated until the thermoplastic resin in the preformed body 19 and the aggregate 35 is sufficiently melted, and in this state, the male mold 37 is inserted into the cavity 39 from the left and right sides of the female mold 38, Move toward the center of 38. Due to the movement of the male mold 37, the preform 19, which has been arranged substantially at the center of the cavity 39, flows toward both openings of the female mold 38,
The state is as shown in the figure. That is, the reinforcing short fibers in the preformed body 19 maintain the orientation orthogonal to the axis of the male mold 37 at the center of the cavity 39, but on both sides thereof, the longitudinal length of the formed body is accompanied by the flow of the thermoplastic resin. The orientation is along the direction. The assembly 35 is provided with a cavity 39 together with the male mold 37.
, But the plain weave cloth 40 remains stationary. In the state shown in Fig. 10, the thermoplastic resin
39 is completely filled, and the movement of the male mold 37 has stopped. When the male mold 37 is further pushed in, the thermoplastic resin is further pressed, and a denser molded body is obtained.

Next, while maintaining the pressurized state, the female mold 38 is cooled to solidify the thermoplastic resin, and then the molded body 24 is taken out.

In the above example, a partition wall is formed at the center of the molded body 24, but in order to obtain a penetrated tubular molded body without a partition wall, the number of the preformed bodies 19 is reduced without using the aggregate 35,
The left and right male molds 37 may be moved until they contact each other.

Embodiment 7 FIG. 11 shows a method of forming the cross-shaped tubular body 32 shown in FIG. This example corresponds to the method according to claims 4 and 5.

The difference between the mold shown in this figure and the mold shown in FIG. 3 is that the upper mold 12 and the lower mold 13 which are female molds have a regular hexagonal shape with a side of 12 mm when both molds are fitted. Hexagonal cavity
43a and 43b are formed, and a regular hexagonal prism-shaped side wall 44 whose one side is 12 mm, which fits both molds with high precision, is provided in the cavity. Other points are the same as those of the mold shown in FIG. The side mold 44 prevents the molten thermoplastic resin from leaking, and presses both ends of the tape 45 previously disposed on the upper and lower surfaces of the cavities 43a and 43b, thereby pressing the tape 45.
It is fixed so that the middle long fiber does not move or loosen, and it guides when the male mold 17 arranged on all sides moves toward the center of the mold, so the center part has a diameter of 16 mm Round hole
46 are provided. Although the male mold 17 has a tip 18 having an outer diameter of 16 mm, the tip may have a truncated conical shape with an inclination angle of 45 ° so that the male dies abut each other at the center of the mold.

A method of manufacturing the cross-shaped tubular molded body 32 using the thus configured mold will be described below.

First, a preform in the form of a tape having a thickness of 100 μm and a width of 4 mm was formed by impregnating nylon 6 into carbon fiber as a short reinforcing fiber, and cutting the preform into a length of 5 to 20 mm.
Next, the cut preformed body is filled into a separately provided mold so that the fiber direction is random in a two-dimensional plane, heated and melted at 250 ° C., and then pressed.
A plurality of different disk-shaped preforms 19 having a thickness of 0 to 24 mm, a thickness of 5 to 10 mm, and a fiber volume content of 60% were formed. On the other hand, tape-shaped preforms cut to a length of 200 mm are superimposed and hot-pressed at 220 ° C to a width of 12 mm.
The tape 45 was formed.

Next, five tapes 45 are respectively arranged on the upper side and the lower side of the cavities 43a and 43b, and a plurality of different preforms 19 are arranged in the cavities 43b of the lower mold 13. Install the mold 44 and then replace the upper mold 12 with the lower mold 13
And integrated by fastening with fixing bolts 20.

Next, the mold is heated to 230 to 250 ° C. to melt the thermoplastic resin of the tape 45 and the preform 19, and the male mold 17
Was gradually moved toward the center of the mold. This male 17
As a result, the molten resin flowed into the cavity in the same manner as in Example 6. The male mold 17 filled with the molten resin in the cavity continues to be pressed, and the pressure applied to the molten resin is 40
kg / cm ² .

After maintaining this pressurized state for about 5 minutes, the mold was cooled to separate the upper mold 12 and the lower mold 13 and the male mold 17 was pulled out to take out the molded body.

The obtained molded body, by the action of bending moment in the arrow direction in FIG. 7, bend where the stress was measured, breaking bending stress 54kg / mm ^2, flexural modulus 4600kg / mm ² and the kind of the molding As very high.

Comparative Example 1 In Example 2, a gate was provided at the center of the mold, and four male dies 37 were arranged and injection-molded to obtain a molded product similar to that of Example 2.

Observation of the molded body showed that the length was 10 ~ before injection molding
Most of the 30 mm reinforcing short fibers were cut or bent to 1 mm or less. The fracture bending stress was as low as about 10 kg / mm ² .

Comparative Example 2 A molded article was produced in the same manner as in Example 7 except that the tape 45 was not used.

The obtained molded article was almost the same in both shape and size as the molded article obtained in Example 7, but the breaking bending strength was 39 kg / mm ² ,
The flexural modulus was 1,700 kg / mm ^2, which was 72% and 3% for Example 7, respectively.
It was only 7%.

[Effects of the Invention] The method for producing a molded article according to the present invention exhibits excellent effects as described below.

(1) Unlike a conventional molding method in which short fibers and a thermoplastic resin are kneaded in an injection molding machine or a molten resin is molded by passing through a narrow gate, a one-way preform is finally formed into a mold. In the obtained molded body, the part to be strengthened in one direction is arranged adjacent to the cavity for molding, and the thermoplastic resin of the preformed body is melted and the split mold is relatively moved, and is included in the one-way preformed body. Since the reinforcing short fibers are flowed together with the molten thermoplastic resin and oriented in the direction of the flow and molded, the orientation of the reinforcing short fibers in the areas requiring strength can be uniformed, and the strength can be reduced. It is possible to easily obtain molded articles of various shapes having excellent strength with less breakage of weld lines and reinforcing short fibers that cause reduction.

(2) When the preformed body contains a reinforcing fiber having a specific length and is formed into a tape or a strand, it is easy to control the orientation direction of the reinforcing fiber, and the molding is performed. The degree of freedom in designing the strength characteristics of the body is increased, and a molded body having a strength distribution close to that of an isotropic material can be obtained.

(3) When using a mold having a female mold having a cylindrical cavity and a male mold inserted into the cavity, a high-strength tubular mold can be used without using complicated and expensive equipment such as an injection molding machine. A molded article can be easily obtained.

(4) In the case where a sheet containing long fibers and a thermoplastic resin is arranged at least on a portion along the inner peripheral surface of the cavity, and a preform is arranged inside the sheet to perform pressure molding,
Since the long fibers are arranged in a portion where a large mechanical stress such as bending acts, high strength can be exhibited as compared with a conventional tubular molded body reinforced only with short fibers.

[Brief description of the drawings]

1 and 2 are longitudinal sectional views of a mold for carrying out the method for manufacturing a molded article according to the present invention. FIG. 3 is a perspective view of a mold for carrying out the method of manufacturing a molded body according to the present invention, and FIG. 4 is a perspective view of a tubular molded body obtained by the mold shown in FIG. is there. 5 to 7 are perspective views of a molded article obtained by the present invention. 8 to 10 are an exploded view of a process, a perspective view of a sheet, and a longitudinal sectional view of a mold for explaining a method of manufacturing the molded body shown in FIG. FIG. 11 is a perspective view of a mold for performing the method of manufacturing the molded body shown in FIG. Description of reference numerals in the drawings 1: upper mold 1 ': molding surface 2: lower mold 2': molding surface 3: cylindrical concave portion 4: hemispherical convex portion 5: hemispherical concave portion 6: side portion 7 : Bowl shaped cavity 8: Preformed body 9: Preformed body 10: Preformed body 11: Inlet 12: Upper mold 13: Lower mold 14: Semicircular cavity 15: Recess 16: Convex 17: Male mold 18: Tip 19: Preformed body 20: Fixing bolt 21: Opening 22: Intersection of formed body 23: Tubular formed body 24: Straight tubular formed body 25: Outer layer 26: Inner layer 27: Middle layer 28 : Y-shaped tubular molded body 29: Main layer 30: Surface layer 31: Hole 32: Cross tubular molded body 34a: Surface layer 34b: Surface layer 35: Assembly 36: U-shaped tape 37: Male 38: Female 39: Cavity 40: Plain weave cloth 41: Long fiber 42: Thermoplastic resin 43a: Cavity 43b: Cavity 44: Side mold 45: Tape 46: Round hole 47: Main layer

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-161529 (JP, A) JP-A-2-229013 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 43 / 02,43 / 18-43 / 20,43 / 34,45 / 02,67 / 14

Claims (8)

(57) [Claims] 1. A plurality of preformed bodies containing short fibers for reinforcement and a thermoplastic resin are arranged in layers in a mold, and heated and pressed to produce a molded body made of a fiber reinforced thermoplastic resin. In the method, a. A mold having at least two split molds is used as a mold. B. At least one of a plurality of preforms has reinforcing short fibers aligned in one direction. Using a one-way preform, c. Placing the one-way preform adjacent to the cavity of the mold, which molds the portion of the molded body where one-way reinforcement is desired, d. Heating the mold Melt the thermoplastic resin of the preform and move the split mold relative to each other.g. Make the short fibers for reinforcement contained in the one-way preform flow together with the molten thermoplastic resin and A fiber-reinforced thermoplastic resin. A method for producing a molded article. 2. The method for producing a fiber-reinforced thermoplastic resin molded article according to claim 1, wherein the one-way preformed article is arranged so that the direction of the short fiber is orthogonal to the moving direction of the split mold. 3. A method for producing a fiber-reinforced thermoplastic resin molded article according to claim 1, wherein a preformed article containing short fibers having a length of 5 mm or more and formed into a tape or a strand is used. Method. 4. A tubular fiber-reinforced thermoplastic resin molded article is molded using a mold having a female mold having a cylindrical cavity and a male mold inserted into the cavity.
3. The method for producing a fiber-reinforced thermoplastic resin molded article according to any one of 3. 5. A sheet including a reinforcing long fiber and a thermoplastic resin is disposed on at least a part of the cavity along the inner peripheral surface, and a preform is disposed inside the sheet and pressure-formed. A method for producing a fiber-reinforced thermoplastic resin molded article according to claim 4. 6. The method according to claim 5, wherein the long fibers are made of carbon fibers. 7. The method for producing a fiber-reinforced thermoplastic resin molded article according to claim 1, wherein a preform molded in a plate shape is used. 8. The method according to claim 1, wherein the short fibers are made of carbon fibers.
The method for producing a fiber-reinforced thermoplastic resin molded article according to any one of the above.